Does my wife have to declare taxes (to get Carte Vitale) if she doesn’t earn anything?

I am a micro-entrepreneur, fully registered and setup here in France, since Oct ‘18. We moved to France from the UK in August 2018. I am expecting to send my first tax return in March. We have paid a company to help with our Carte Vitale, particularly for my wife who does not work at all here in France or anywhere else. She is totally dependant on my income.

We were told that our family household income will be used to work out the % she has to pay to social services to receive her Carte Vitale, but we have also been advised that she should try and get into the tax system this May when tax declarations occur. How would we do that, as she doesn’t receive any income?